What I meant was that only, the meter IC is a comparator, it sees the input and reference and tells you what it thinks is the input.
If your reference is wrong, it will give you wrong results.
Anyway, back to topic...
Waiting for his post, and given +/- 48 Volt rails, looks like a 7293 will be too close to the limit. so a 49810/30 would be more suitable.
But the transformer will give 75 VA or so, maybe less than what the chip will need...
If your reference is wrong, it will give you wrong results.
Anyway, back to topic...
Waiting for his post, and given +/- 48 Volt rails, looks like a 7293 will be too close to the limit. so a 49810/30 would be more suitable.
But the transformer will give 75 VA or so, maybe less than what the chip will need...
The ST TDA7293 datasheet tells +/- 60 Vdc as the maximum supply voltage without load and +/- 50 Vdc as the maximum supply range. So +/- 48 Vdc are well within it's limits. Somewhere else in the chipamp section there's a discussion about a board that features two 7293's in parallel. As the chip isn't that expensive, I'd go for that.
Best regards!
Best regards!
TDA 7293 will give nearly 100 watts at that voltage.
His transformer is 75 VA
Or he can connect the 0-34 windings, put another bridge, which will give him +/- 24 Volts, and drive a larger variety of chip amps with lower output.
The existing bridge seems to be accross the 34-0-34 windings, with 0 to ground or whatever.
Also both windings can be used to drive a BTL circuit, with two chips.
But I am stil waiting for his post...
At +/- 24 volts, 1875 or 3886 would do well, even for 4R loads.
His transformer is 75 VA
Or he can connect the 0-34 windings, put another bridge, which will give him +/- 24 Volts, and drive a larger variety of chip amps with lower output.
The existing bridge seems to be accross the 34-0-34 windings, with 0 to ground or whatever.
Also both windings can be used to drive a BTL circuit, with two chips.
But I am stil waiting for his post...
At +/- 24 volts, 1875 or 3886 would do well, even for 4R loads.
His main issue was noise, and it progressed from there.
He wants to use what he can from this unit, and improve or update it.
And a new amplifier module if purchased ready made would have the heat sink in place.
Then it becomes a mechanical thing, how to fit in place in the space available and so on.
He wants to use what he can from this unit, and improve or update it.
And a new amplifier module if purchased ready made would have the heat sink in place.
Then it becomes a mechanical thing, how to fit in place in the space available and so on.
That´s called a "Musical Instrument Combo Amplifier"
68VAC and 2.2A are worth 150VA ... ample rating for a 75W amplifier.
not sure why they waste ink toprint that unusable rating.
Now we are talking.
I call that "close to the edge"
And Industry experience shows that TDA729x amps trying to put out maximum power tend to be unreliable (Marshall got quite burnt by them, Behringer and Loudbox too) while ifn you use themwith lower rail voltage (think +/-42V or so) they tend to live long life.
Derating anything never hurts.
See above.
Please avoid kludgy ideas, the OP is trying to replace current power amp, feeding it from current power supply.
You´d be surprised at the heatsinking provided by a thick (think 2.5 or 3 mm) *aluminum* backplate, held vertical, one face "outside", the other "inside" but probably with lots of slots/vents.
So good that it´s very common in MI amplifiers and some powered cabinets.
I do not read that descriptuon as a complaint about noise (hiss-hum-buzz) but a description of distortion.
Odd thing is that he still has not posted.
At that voltage, a transistor amp may also be suitable.
That thing is a portable guitar amplifier, not much of a guitar scene here, and the amps tend to be local.
So it is basically a salvage or nostalgia thing, maybe he will use it to listen to the radio, whatever.
At that voltage, a transistor amp may also be suitable.
That thing is a portable guitar amplifier, not much of a guitar scene here, and the amps tend to be local.
So it is basically a salvage or nostalgia thing, maybe he will use it to listen to the radio, whatever.
I multiplied 34V and 2.2A per winding to get 75 VA.
I have a Sansui set which has the STK module driving transistors.
That sort of design may work, but here I think the 49810/30 will be comfortable, those are rated for +/- 100 volts, 48 is not near its limits.
And it will not over load the supply.
Ready modules may be available in his location.
I have a Sansui set which has the STK module driving transistors.
That sort of design may work, but here I think the 49810/30 will be comfortable, those are rated for +/- 100 volts, 48 is not near its limits.
And it will not over load the supply.
Ready modules may be available in his location.
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